'Let anyone be administrator' bug in VMware snapped shut

VMware has published a security update for its virtualisation software including its ESX, Workstation, Fusion and View products.

A range of applications made by the EMC-owned vendor should therefore be patched to squash a privilege-escalation vulnerability in the VMCI.SYS driver. The flaw affects host machines running Microsoft Windows and guests running the Redmond operating system.

A malicious local user can, thanks to the bug, manipulate and exploit memory allocations using the Virtual Machine Communication Interface (VMCI). As a consequence an attacker can carry out actions that would normally be restricted to a system administrator, such as configuring the host environment or manipulating guest systems on the machine.

But it does not appear to be a hypervisor escape bug: that is, it may not be possible to exploit the hole to leap from a guest into the host environment and thus attack the server running the virtual machines. VMware's VMCI driver is present in the host and guest Windows operating systems and, presumably, this latest vulnerability allows a user local to the guest or host to ramp up their access rights within their respective guest or host environment.

VMware's security advisory has more on the issue in some depth here. The virtualisation firm credits Derek Soeder of Cylance and Kostya Kortchinsky of Microsoft for independently reporting the security bug. ®